Origin and relationship between different cell types in malignant fibrous histiocytoma.

The derivation of histiocyte-like cells in malignant fibrous histiocytoma (MFH) has been a matter of debate. To shed light on this problem two cell lines from two subsequent recurrencies of MFH were established. The existence of two different cell populations, mainly fibroblast-like in the first cell line and mainly histiocyte-like in the second, was shown by light and electron microscopy, DNA measurements, and karyotype analysis. By detailed banding analysis and identification of several identical chromosomal marker types in the two cell lines, it was proven that they originally derived from the same single cell or single clone. Because the first cell line, with mainly fibroblast-like cells, was in the hypotriploid region and the second, with mainly histiocyte-like cells, was in the penta-hexaploid region, the data explained the appearance of histiocyte-like cells in MFH as a consequence of chromosomal progression.